Applicants have discovered (see parent Patent No. 4,238,360) that ammoniated cogels of the SiO.sub.2 /Al.sub.2 O.sub.3 ratio in the range of less than 3 and preferably more than about 1 when exchanged with a monovalent or polyvalent cation, preferably a rare earth cation, to reduce the NH.sub.3 content to less than 0.3 equivalents per mol of Al.sub.2 O.sub.3 have substantially improved cracking activity as compared with the ammoniated cogel prior to such exchange. The prior art relating to the use of silica-alumina gels as cracking catalyst is cited in the parent U.S. Pat. No. 4,238,360.